Gas anchor



Ap 14, 1964 L. J. s. JONGBLOED ETAL 3, 28,719

GAS ANCHOR Filed May 5. 1961 INVENTORS: L J SCHMIT JONGBLOED E. A. vos BY:H,h Q-|/&

THEIR AGENT United States Patent Ofi ice 3,128,719 Patented Apr. 14, 1964 3,128,719 GAS ANCHOR Lotlewijk J. Schmit Jonghloed and Eduard A. Vos, Delft,

Netherlands, assignors to Shell Oil Company, New

York, N.Y., a corporation of Delaware Filed May 5, 1961, Ser. No. 108,113 Claims priority, application Netherlands June 13, 1960 4 Claims. (Cl. 103-203) This invention relates to gas anchors and pertains more particularly to gas anchors and separators adapted for use in the pumping of oil wells.

A pumping well is normally equipped with a string of easing, a string of tubing depending within the casing, a pump attached to the lower end of the tubing string and a gas anchor attached to the pump over the suction inlet of the pump, the object of the gas anchor being to promote better separation of gas from the oil by providing a long and tortuous path to the suction end of the pump.

Oil flowing into the bottom of a well often contains large quantities of gas which, unless separated from the oil, are drawn into the pump. The displacement capacity devoted to the compression of this gas in a pump reduces its liquid capacity. Also, the power required to compress any free gas entrained with the oil drawn into an oil well pump is largely wasted. It is therefore necessary, insofar as is practical, to exclude the entry of gas from the pump in order to minimize the size and initial cost of the pumping system as well as the operating and maintenance costs.

Since pump eificiencies and capacities are adversely affected by the depth of the well, the trend toward deeper wells increases the need for better gas-liquid separation at the pump. Furthermore, the trend toward drilling wells of smaller diameter adds emphasis to the need for better separation of the oil and gas by means of a gas anchor, as it is well known that the performance of gas anchors in present use is directly related to the hydraulic radius of the gas anchor down-pass which is limited by the oil well bore. In modern oil well pumping, liquid displacement efliciencies of less than 60 percent are by no means uncommon, even though attention has been given to securing gas anchors of the best available types.

It is therefore an object of this invention to provide an improved gas anchor or separating device of simple and rugged design adapted to separate gas from oil that is to be pumped.

Another object of this invention is to provide an eflicient gas anchor of large capacity for a given diameter which can be readily attached to a well pump to be located near the bottom of a well.

A further object of this invention is to provide a gas anchor of such design that high separation efficiency is maintained when anchors of small diameter are used. It is apparent that the greater the amount of gas separated from an oil-gas mixture by means of a gas anchor prior to passing the mixture in a well pump, the greater amount of oil which can be pumped per unit time by the well pump.

These and other objects of this invention will be understood from the following description of the preferred embodiment of the invention when taken with reference to the drawing, wherein a diagrammatic view of the gas anchor of the present invention is illustrated as being connected to the bottom of a pump and positioned in a well casing.

The present invention relates to a gas anchor consisting of a cylindrical housing sealed at the bottom, at least one sheet metal helix accommodated in the housing, and a tube, one side of which communicates with the space underneath the sheet metal helix. According to the invention, a gas discharge conduit is centrally positioned in the housing, which conduit is provided with openings, preferably near the side of the sheet metal helix facing the bottom of the housing. Preferably the top of the helical channel between the housing, the gas discharge conduit and the sheet, communicates with the outside of the housing.

Referring to the drawing, a Well pump 10 is shown as having attached thereto the housing 11 of a gas anchor and positioned in a production well provided, for example, with a casing 12. This casing communicates, in a manner not further shown, with the pore space of an oilbearing formation traversed by the well. An oil discharge conduit 14 leads from the space 13 at the bottom of the housing 11, the conduit communicating at its other end with the suction side of the well pump 10. Of this pump only the suction valve 16 is shown. It is not necessary to arrange the conduit 14 centrally in the housing 11, as shown in the embodiment in the drawing; if necessary the conduit can be led along the outside of the housing 11.

The gas discharge tube 17 is arranged round the oil discharge conduit 14. If desired, the gas conduit may be sealed at the bottom. Between the housing 11 and the conduit 17 are arranged one or more, for example, two sheet metal helices 18a and 18b in such a way that between the inner wall of the housing 11, the outer Wall of the conduit 17 and the sheet metal helices 18a and 18b two helical channels are formed, the bottoms of which communicate with the space 13 at the bottom of the housing 11. Openings 19 are arranged in the conduit 17 under the sides of the sheet metal helices 18a and 18b facing the bottom of the housing 11. These openings 19, of which only a few are shown in the drawing, are arranged in the conduit 17 in the part over which the sheet metal helices 18a and 181) are arranged.

On a level above the sheet metal helices 18a and 18b, supply openings 20 are provided in the wall of the housing 11, via which openings the outside of the housing 11 communicates with the top part of the helical channels. The gas discharge conduit 17 runs sideways into the wall of the housing 11, preferably at the point 21 on a level located above the supply openings 20.

The apparatus according to the invention operates as follows:

A mixture of oil and gas flows upward from the formation through the annular space 22 between the inner wall of the casing 12 and the outer wall of the housing 11.

A great portion of the gas in the mixture escapes from this mixture in the area where the openings 20 are arranged. This gas fiows via the annular space 15 between the tubing (not shown) and the casing 12 to the wellhead. The mixture entering the housing 11 via the openings 20 contains a considerably smaller, but still undesirable amount of gas. After flowing through the openings 20 the mixture passes downwardly through the helical channels between the sheet metal helices 18a and 18b to the bottom of the housing 11; thence the oil is sucked up by the pump 10 through the conduit 14.

During the passage of the mixture through the helical channels the heavy component of the mixture (the oil) is forced towards the inner wall of the housing 11, and the light component (the gas) moves to the center line of the housing 11. The light component (the gas) escapes through the openings 19 to the space between the conduits 14 and 17, and flows upward through it to the opening 21 which opens into a zone 15 where the gas already separated from the mixture at the openings 20 flows upwards. The oblique position, shown in the drawing, of the sheet metal helices 18a and 18b is adjusted to the movement of the gas bubbles insofar as it is caused by the co-action of centrifugal force and gravity, and thus favors 3 the removal of the gas from the mixture. The amount of gas in the mixture decreases with increasing downward flow of mixture, until the latter is sucked up by the pump 10 from the bottom space 13 of the housing 11 through the conduit 14. The invention is not restricted to gas/ oil separators provided with two sheet metal helices.

In an experimental arrangement in which the outside diameter of the helical channels was 7.5 cm., mixtures of varying gas/ oil ratios were supplied to a gas anchor according to the invention. The quantity of oil passing the separator per hour was from 1 to 1 /2 cu. meters,

When dispersions having gas-oil ratios of between 5 and 20 were supplied, the gas/oil ratio of the mixture flowing through conduit 4 was less than 0.01.

Gas/ oil mixtures of the same composition and quantity were supplied to a separator of similar dimensions but of different design. The gas/oil ratios of the mixtures passing through the conduit 14 were between 0.06 and 0.3.

We claim as our invention:

1. For use with a well pump having fluid inlet means thereto, a gas anchor comprising: a tubular housing member closed at the lower end and having fiuid port means through the side Wall thereof; gas conduit means fixedly secured to and axially disposed within said housing member, the upper end of said conduit means being directed to and through the side wall of said housing member above the port means therein; downwardly opening spirally trough channel means formed on the outside of said gas conduit means throughout a substantial portion of the length thereof, said channel means extending substantially to the inner wall of said housing member; fluid openings through the wall of said gas conduit means at locations near the top of said trough channel means; and, an imperforate delivery tube carried by said housing member, said delivery tube extending axially through said gas conduit means in spaced relationship therewith, said delivery tube having its lower end open to the space within the housing member near the lower closed end thereof and having its upper end in open communication with the fluid inlet means of a well pump.

2. A gas anchor for use in wells, said gas anchor comprising: a cylindrical housing having a closed lower end and having fluid port means through the side walls thereof; at least one helical member carried within said housing and extending over a substantial length thereof to form an inverted troughlike fluid flow channel; a gas discharge tube centrally positioned within said housing, said gas discharge tube extending through and in contact with said helical member, the upper end of said gas discharge tube extending through the wall of said housing above the helical member therein and being in open communication with the space outside the housing; said helical member sloping upwardly from the housing wall with the bottom surface of the helical member at all times forming an acute angle with the longitudinal axis of said discharge tube; a plurality of openings through the wall of said discharge tube at levels just below the points where the buttom surface of said helical member contacts the discharge tube; and, an imperforate delivery tube carried by said cylindrical housing, said delivery tube having its lower end open to the space within said housing near the closed lower end thereof and having its upper end in open communication with the fluid inlet means of a well pump.

3. The apparatus of claim 2 wherein said fluid port means includes a plurality of fluid ports through the wall of said housing above the helical member carried therein and below the point at which the upper end of said gas discharge tube extends through the wall of said housing.

4. The apparatus of claim 3 wherein said delivery tube extends axially through said gas discharge tube and is in spaced relationship therewith.

References Cited in the file of this patent UNITED STATES PATENTS 1,628,900 Neilsen May 17, 1927 2,104,339 Arutunoff Ian. 4, 1938 2,147,671 Pratt Feb. 21, 1939 2,398,339 Watts Apr. 9, 1946 2,652,130 Ferguson Sept. 15, 1953 2,843,053 Carle July 15, 1958 2,993,480 Huet July 25, 1961 

1. FOR USE WITH A WELL PUMP HAVING FLUID INLET MEANS THERETO, A GAS ANCHOR COMPRISING: A TUBULAR HOUSING MEMBER CLOSED AT THE LOWER END AND HAVING FLUID PORT MEANS THROUGH THE SIDE WALL THEREOF; GAS CONDUIT MEANS FIXEDLY SECURED TO AND AXIALLY DISPOSED WITHIN SAID HOUSING MEMBER, THE UPPER END OF SAID CONDUIT MEANS BEING DIRECTED TO AND THROUGH THE SIDE WALL OF SAID HOUSING MEMBER ABOVE THE PORT MEANS THEREIN; DOWNWARDLY OPENING SPIRALLY TROUGH CHANNEL MEANS FORMED ON THE OUTSIDE OF SAID GAS CONDUIT MEANS THROUGHOUT A SUBSTANTIAL PORTION OF THE LENGTH THEREOF, SAID CHANNEL MEANS EXTENDING SUBSTANTIALLY TO THE INNER WALL OF SAID HOUSING MEMBER; FLUID OPENINGS THROUGH THE WALL OF SAID GAS CONDUIT MEANS AT LOCATIONS NEAR THE TOP OF SAID TROUGH CHANNEL MEANS; AND, AN IMPERFORATE DELIVERY TUBE CARRIED BY SAID HOUSING MEMBER, SAID DELIVERY TUBE EXTENDING AXIALLY THROUGH SAID GAS CONDUIT MEANS IN SPACED RELATIONSHIP THEREWITH, SAID DELIVERY TUBE HAVING ITS LOWER END OPEN TO THE SPACE WITHIN THE HOUSING MEMBER NEAR THE LOWER CLOSED END THEREOF AND HAVING ITS UPPER END IN OPEN COMMUNICATION WITH THE FLUID INLET MEANS OF A WELL PUMP. 